Human skeletal muscle acylphosphatase, purified by a technique based on affinity chromatography on immunoadsorbent, has been sequenced completely using tryptic and peptic peptide series, prepared by reverse-phase high-pressure liquid chromatography. The sequence analysis was carried out on all the isolated tryptic peptides using a manual Edman degradation technique and time-course analysis of the released amino acids by carboxypeptidase A. The enzyme is NH2-blocked and the blocking group has been identified by fast atom bombardment mass spectrometry.